avcodec/v4l2_m2m: handle v4l2 end of stream event

When flushing the capture buffers, the driver may send a V4L2_EVENT_EOS
to notify that draining is completed. Currently, v4l2_m2m does not
subscribe to this event, which can cause some devices (i.e. imx8qm) to
hang at the end of encoding/decoding. Support for handling the event is
added in this commit.

Some devices may not signal V4L2_EVENT_EOS. This is logged as a warning
message during initialization and not treated as a fatal error.

Signed-off-by: Ming Qian <ming.qian@nxp.com>
Signed-off-by: Andriy Gelman <andriy.gelman@gmail.com>

1 files changed, 7 insertions, 0 deletions

diff --git a/libavcodec/v4l2_m2m_dec.c b/libavcodec/v4l2_m2m_dec.c
index c5ee86b993..3e17e0fcac 100644
--- a/libavcodec/v4l2_m2m_dec.c
+++ b/libavcodec/v4l2_m2m_dec.c
@@ -123,6 +123,13 @@ static int v4l2_prepare_decoder(V4L2m2mContext *s)
         }
     }
 
+    memset(&sub, 0, sizeof(sub));
+    sub.type = V4L2_EVENT_EOS;
+    ret = ioctl(s->fd, VIDIOC_SUBSCRIBE_EVENT, &sub);
+    if (ret < 0)
+        av_log(s->avctx, AV_LOG_WARNING,
+               "the v4l2 driver does not support end of stream VIDIOC_SUBSCRIBE_EVENT\n");
+
     return 0;
 }